Hi folks:

I'm working on a record that has me puzzled. It's a Gennett record from 
1923. The authorities say that Gennett didn't take up electrical 
recording until 1926 or so, so I had  this pegged as acoustic.

But it has *hum* on it. Significant hum; at this stage in processing the 
signal (two channels combined, no EQ, iZotope de-clicking applied) the 
hum signal is at about -38dBFS (about 24dB below my nominal 0vu level). 
There's also an intermittent signal at 40Hz. The lowest signal frequency 
seems to be about 150Hz

If this is an acoustical recording, how did those low frequencies get 
onto the record? If there was a mechanical rumble in the room, I would 
not expect the recording horn to respond significantly at 57Hz, let 
alone 40Hz. (Heck, 150Hz is surprising.)

And the thing is, it doesn't *sound* like an acoustical recording -- 
there aren't the typical horn resonances coloring the sound. It sounds 
like a good early electrical recording.

But the 1923 date is reinforced by several sources -- well before 
Gennett is believed to have gone electric.

Could this have been an experimental electrical recording (perhaps using 
the GE Photophone process) that somehow escaped into the catalog? Could 
it be turntable rumble during cutting? If so, why does the record sound 
electrical rather than acoustical?

By the way, the flip side has virtually identical hum, though a cursory 
glance doesn't show the 40Hz component.

Anyhow, I'm mystified. I know that record companies were experimenting 
with electrical disk recording before the majors adopted the Western 
Electric system, hence my speculation that this could have been one of 
those experiments.

Any ideas?

Peace,
Paul Stamler
St. Louis

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus